Color reaction type duplication process



copies on a duplicating machine by a Un ted Stew Patent Q" COLOR REACTION TYPE DUPLICAT'ION PROCESS Richard G. ,Maguire, Chicago, and Glen W, Hedrick, Glen Ellyn, Ill., assignors, by mesne assignments, to Ditto, Incorporated, a corporation of Delaware No Drawing. Application June 22, 1951 Serial No. 233,106 H Ihe'invention relates to a method of duplicating, and more particularly relates to a method of duplicating wherein an impression sheet and a master sheet having an image thereon are contacted and a reproduction of the image is formed on the impression sheet 'by the reaction of a component in the image material with' a component on the impression sheet.

'Various materials have been suggested for use in the image material and on the impression paper for bringingabout a chemical reaction that will produce acolor, the term color" being used herein to include black. Many of the materials have been suitable for producing one or two-copies of good color intensity, and some have'pro- .duced'by hand methods several copies of fair colorintensity. 1:;HOW6V6I', so far as is known a large number of high intensity copies by a color reaction process has not been-attained by duplicating machines,- due at least in part to the short time of contact of the mastersheet and impression sheet required by such machines, to the small amount of liquid used, and also in general to the pressure of contact being less in' the machine process than in the hand process. In those instances, in which oleaginousor other hydrophobic material is present with the color reactant, the attainingof .a large number of high intensity copies is particularly difficultevenby ha'nd methods.

An .object of this invention is to provide a new and commercially valuable duplicating process.

Another object of this invention is the provision ofa facilitate control of the shade of color. They arepreferably used in solutions having pH of from 4 through 8.

'-lnstead of using the nickel salt in the image material and the rubeanic acid on the copy sheet,,the nickel salt may be used on the copy sheet and the rubeanic acid in p the image material.

' nickel salts, but not the preferred black copies, may be" obtained with rubeanic acid and other heavy metal salts:

Also instead of moistening the copy sheet with a solu tion of the rubeanic acid or nickel salt, the reactant, may be coated on'the copy sheet either by surface coating or by impregnation of the sheet or the pulp from which it is made. p

Similar results to those obtained with'rubeanic acid and such as copper, cobalt, and also with alkyldithiooxamides such as monomethyl and diethyl oxamides'i and heavy metal salts. 'Also glyoximes'with heavymetal salts par- The alkanol amines and their Weak acid salts are par- 7 ticularly useful in all processes wherein heavy metal salts, and particularly nickel salts, are reacted with color reactants such as dithio-oxamides and glyoximes in nonaqueous or largely non-aqueous solvents. The use of transfer liquids which contain only small proportions of water is an advantage in reducing curling of copy paper, and moreover, for rubeanic acid duplicating processes wherein one solution is used for both transfer and color reaction or development, it becomes necessary tokeep the to maintain the rubeanic acid water content low in'orde'r' in solution.

The'alkanol amines, even in largely aqueous transfer fluids and buffering agents.

With solutions which arelargely aqueous other buffering agents may be used, the'most suitable being the am methodiof producing a large number of high intensity color. reaction type of duplicatingrprocess. f

Another object is the provisionof a method of obtaining a large number of high intensity copies by a color reaction duplicating process in which the image on the master copy'is formed of a color reactant mixed with an oleaginous material. Y A further object is to providea method of producing black. copies without discoloration ofrthe copy paper- Other objects and advantages of the invention will become' apparent-as thefoll'owing description progresses.

In,ac cordance with one embodiment of my invention a master sheethaving animage formed of acomposition' containinga nickel salt is contacted with .copy sheets lnqisienfidnwith a solution of rubeanic acid (dit-hioorgan;ideJgin asolvent for thenickel salt. Black reversed reproductions of the image are obtained on thetcjopy- .for machine duplication and jthe production of a large number, of high; intensity copies (improved ;,black with rubeanic acid and nickel salts) {there is incorporated in;

thepolor reactant solutionan ;alkanol'amine,,'or an antethanol.v amine triethanol amine and dimethanolamine jor' tlie'iweak acid salts thereof. These-materials initiate complex formation-of the metal with the rubeanic acid and pression paper'to develop the color.

monium salt buffers such as ammonium acetateand am-f moniuni citrate. Also other materials which aid transfer may beused with them, as for example, surface active. agents. However, since rubeanic acid is not soluble in water, it then becomes advisable to usea two-step process in which the surface active material is first applied to the impression paper, the impression paper applied to the master. sheet to bring about transfer of the image material, and then rubeanic acid in its solvent applied to the im- However, when diethanolamine'islused the diethanolamine is dissolvedin arr-aqueous solution containing a major proportionof ethyl and/or methyl alcohol, this solution mixed with a solution of rubeanic-acid in tetrahydrofurfuryl alcohol,

and the resulting mixture applied to the impression paper, which is thencontacted with the image on-the master sheet." Due'to thei factthat there is a slow decomposiilOIl',Of rubeanic acid in the presence of diethanol amine,

it is preferable=to mix the twoingredients immediatelybefore applying, to the impression paper.

The preferred solvent for the rubeanic acid is tetrahydrofurfuryl alcohol. This was found to be the best non-toxic solvent. Acetone may also be used, but this is not-asgood a solvent as the tetrahydrofurfuryl alcohol,- and is also somewhatof afire hazard. Tetrahydro furane is' a good solvent for rubeanic acid but has the disadvantage of being more volatile than is generally desirable foroifice duplication.

Patented May 17, 1 p

V solution, have the advantage that'they greatly increase transfer,- especially of nickel salts, and apparently act as combined 'The'preferred 'heavy metal salts are the watersoluble salts, particularly the chlorides andi'sulfates, although f the acetates and other salts may be used. With rubeanic acid and its homologues, particularly satisfactory results have been obtained with nickel chloride and nickel sulfate. Nickel sulfate has the advantage over the chlorideof being less hygroscopic.

The image material'may be made of various formulae, and may be applied to the master sheet in several Ways. Preferably the image material comprises a mixture of the color reactant with hydrophobic material such as wax and oil. In order to obtain increased copy strength the composition may also comprise a hydrotropic material such as thealkali metal salts of xylene, benzene, toluene and p-cymene sulfonic acids. In order to obtain good dispersion of the color reactant, particularly the inorganic color reactant with the oleaginous materials, a dispersing or emulsifying agent may also be used. The non-ionic and cationic surface active agents give more uniform and stable dispersions than the anionic type and are therefore preferred. The buffering agent may be included in the image material. maybe added, if desired.

The image material may be applied in the form of an image to the master sheet in several ways. For example, the image material may be coated on a ribbon to form a typewriter ribbon and the image produced on the master sheet by direct typing. In this case a duplicating machine would be used having an otfset blanket which would receive a negative impression from the original image impression on the master. Color reactant would then be applied to a series of impression sheets and the impression sheets contacted with the image on the blanket so that each sheet picks up from its negative a corresponding positive impression. Instead'of using an ordinary rubber or like offset blanket a hectograph blanket may beused.

- 'In the preferred embodiment of the invention, the image composition is coated on a paper sheet to produce an impression transferable transfer sheet or carbon paper. Suitable carbon paper of this type is made by mixing a small proportion of the .color reactant with any of the oleaginous compositions used to make ordinary carbon paper, preferably also using, as above pointed out, hydrotropic material and/or nonionic or cationic dispersing agents. Examples of suitable carbon paper'and typewriter ribbon formulae are given below. This carbonpaper' may be used to produce positive. image impressions on a master sheet which may be used for offset duplication but preferably to produce on'a master sheet anegative or mirror reverse image of the matter to be duplicated. The method of doing this is Well known in the hectograph and spirit process duplicating art, and involves simply the placingof a sheet of paper against the coated surface of the suitably prepared carbon paper, and then typing or writing on the side of the sheet of paper which is not in contact with the carbonpaper. The typing may be carried out with an ordinary ribbon in the typewriter. The pressure of thetype as the writ-v ing takes placecauses'a mirror reverseor negative impression image to be made on the surface of the sheet in contact with the carbon paper coating. This sheet, called the master sheet, is placed on the drum of a direct process duplicating machine and copiesmade in'the usual manner by contacting copy paper moistenedwith a solution of the reagent .which reacts with the reagentin the image material on the master. In'the'preferred embodiment of the invention, the color reactant in the image material is a water soluble nickel salt and the reagent which is applied to the paper is rubeanic acid.

'There are described below a number of typical formulae for carbon paper, typewriter ribbons and Writing. inks. These formulae are merely illustrative of types of image material or inks which may .be used in carrying out this invention, it being understood that these formulae illustrate several embodiments whichhave given Pigments, fillers and the like also satisfactory results and are not intended to restrict the invention thereto.

1 Batch Pounds Item No. Ingredients Charge, per 1,000-

grams pounds ink Nickel sulfate hexahydrate 180 600 Alkaterge C (substituted oxa- 3" l zoline). Gum Arabic. 3. Red Z Oil 7 51 170 Carnauba W 33 110 Beeswax 6. l Lanolin- Sugar. Castor Oil Sodium-p-eymene sultonate- Red Z .Oil

1 Charge for each 100 grams of base ink from items 1 to 8.

Red Zoil in the above table is a mineral oil of A.P.I., gravity 29,3, viscosity 19.5 seconds Saybolt at 100 F.

The procedure for making carbon paper using the above formula is as follows:

(a) -The two grinding rolls of a three roll paint mill are heated to approximately 200 F. by passing water;

at 200 F. through they rolls. The hot water issupa. plied by mixing steam and cold city water. The temperature is controlled by a mixing valve.

(b) The materials including items one to eight only:

are added, to the mill and grinding started. Shortly after starting. the mass becomes fluid. The rolls are set so thata heavy film of liquid is carried on'the rolls. After about fifteen minutes all the batch is taken off.

water.

is repeated about three times, the batch is well mixed. If not, the operation is continued until the ink is thoroughly mixed.

(c) The dope. is weighed and put back on the hot mill.

Items 9 to 11 then are added. The charge is based on each 100 grams of base ink obtained from the above contacted by the fluid are preferably made ofaluminum or" The outlet of each pumpis attachedto operation. has been reduced to seven gauge or less.

.(d) The'ink taken off the cold roll is flaky in appear ance'and is ready for coating.

(e) An aliquot (3 to 4 grams) of the ink is melted and allowed .to cool to room temperature and stand overnight before testing.

The duplicating may be carried out using any of the well known spirit process duplicating machines-modified by having the fluid tank and pump replaced by two smaller tanks and pumps. Metal parts of the machine stainless steel. a T-tube.

In the preferred processofthis invention involvingthe use of rubeanic' acid as the color reactant'or developer to be applied to the impression sheet and the use of diethanolamine as the buffer and transfer fluid, the

rubeanic acid and the diethanolamine are mixed together immediately before applying to the impression paper.

A suitable diethanolamine c'ornpositionis as followsz Parts by volume; Water; 60 Methanol 20 Diethanolamine 20;,

Milling is continued until the particle size A suitable rubeanic acid composition is as follows: Tetrahydrofurfuryl alcohol 40 parts by volume. 1

Instead of mixing the two solutions together and applying the mixed solution to the copy sheets, the process may be carried out in two steps, consisting of first applying to the copy paper a transfer fluid which will dissolve and transfer a portion of the color reactant of the image material to the paper, and then applying to the treated paper a developing fluid containing an ingredient which reacts with the transferred color reactant to produce a color. A suitable transfer fluid consists of water30 parts, diethanolamine parts, diethylene glycol 20 parts, tetrahydrofurfuryl alcohol 20 parts, and methanol 20 parts, all by volume. A suitable developing solution consists of a, 2% solution of rubeanic acid and a mixture of tetrahydrofurfuryl alcohol 40 parts, diethylene glycol 20 parts, and methanol 20 parts," all by volume.

In the above compositions water, d-iethanolamine and rubeanic acid are the most important components of the combined fluids. Elimination of any one results in greatly decreased intensity of the copies. Diethylene glycol and tetrahydrofurfuryl alcohol adds slightly to copy intensity."

Substitution of acetone for tetrahydrofurfuryl alcohol has little or no effect on copy intensity and greatly increases drying speed of the copy.

The proportions of the above ingredients may be varied widely. The rubeanic acid may be used in a 1% or less solution in a solvent, and the amount of rubeanic acid solution required for satisfactory copy .intensity is of the order of 5 cc. per-20 copies.

The following example illustrates another ink formulation and another transfer fluid and development fluid which has-also been foundto be satisfactory.

H. INK FORMULATION 2. Procedure The procedure is essentially the same as that described in part I. The ingredients are weighed and added at once onto a hot mill and milled to a'seven gauge or less by allowing the material to melt down, grinding for a short while and taking off the cold roll. This is repeated until mixing and grinding is complete.

The preparation of carbon papers is the same as in part I.

The major differences in this process compared to that described in part I are the type of fluid-s employed and the procedure for making copies.

6 (a) Fluid composition: 6

"Transfer fluid- 1:1 water-ethanol mixture by volume Diethanolamine 2 parts 1 5 Igepal C.A. ethylene oxide condensation product with an alkylated phenol 1 part 1 Unit weight per 100 cc. mixed solvent. '(b) Development fluid:

2:3 tetrahydrofur-furyl alcohol ethanol mixture (by volume) 1 Rubeanic acid 2 parts 1 1 Unit weight: 'per 100 00. mixed solvent. The proportions of ingredients in the transfer and developing fluid may vary widely, the essential ingredients being simply'a solution of rubeanic acid in a solvent which will dissolve or transfer the nickel salt. The solution will ingeneral contain water, as well as an organic solvent for the rubeanic acid. It is desirable, however, to keep the water content low in order to eliminate curling of the paper, and this is done by using ethyl or methyl alcohol and other volatile solvents which alone or in thev invention except insofar as included in the accompanying claims. I

We claim:

ing to a copy sheet an alk-anol amine and rubeanic acid,

and contacting said copy sheet with a master sheet-having thereon an image of a composition comprising an oleaginous material and a water soluble nickel salt.

. 2. The method of duplicating which comprises moistening a copy sheet having thereon rubeanic acid with a solution of an alkanol amine, and contacting the copy sheet witha master sheet having thereon an image of a composition comprising an oleaginousmaterial and a nickel salt.

in the file of this patent UNITED STATES PATENTS Kretschmann May 7, 1901 Hickman July 11, 1933 Gookin et a1 Mar. 13, 1934 Lejeune Jan. 28, 1936 Lierg Apr. 7, 1936 Glas Apr. 21, 1936 Neidich Feb. 14, 1939 Antrim Sept. 3, 1940 Neidich Oct. 8, 1940 References Cited Bour Apr. 29, 1941 Bour Dec. 29, 1942 Kohn Apr. 13, 1943 Studeny Dec. 27, 1949 omen REFERENCES Lange: Handbook of Chemistry, 3rd 64., 1939, HandbookPublishers, Inc., Sandusky', Ohio,

1. The method of duplicating which comprises apply- Collins Nov. 26, 1940 

